Pallets are used to facilitate the lifting and transportation of loads by a forklift or similar lifting machine. Softwood pallets are widely available and easily constructed, but because of the variability of timber characteristics the load carrying capacities and lifetime of a wooden pallet are unpredictable. Furthermore, when, due to ordinary wear and usage a wooden pallet must be junked, there is very little salvage value in the scrap wood. Plastic pallets have the advantage of consistent physical characteristics and load-carrying capacity and also have a longer life than wooden pallets. A sturdy plastic pallet such as that disclosed by U.S. Pat. No. 4,428,306, incorporated herein by reference, may be produced using a twin-sheet thermoforming process. That pallet has integral depending feet which extend beneath the load bearing member of the pallet to provide clearance space for the insertion of the arms of a forklift.
Certain portions of a pallet are exposed to greater wear than others, for example the feet. To increase the life of the pallet it is desirable to make these portions of greater strength. Plastic sheets when molded in the thermoforming process are typically reduced in thickness as the sheet is drawn into cavities of the mold to form projecting portions of the molded product such as pallet feet. Because the standard thermoforming process uses sheets of a constant thickness, it is not possible to substantially increase the thickness of one portion of the molded product without increasing the thickness of all portions, with a commensurate increase in the cost and weight of the product. Pallets have been reinforced with metal and molded plastic inserts or reinforced with fused plastic strips. Pallets reinforced with foam reinforcements or with nonplastic materials such as steel, wood, or fiberglass are also known to the art, but these composite pallets are costly to recycle, as the foam or nonplastic components must be separated from the recoverable plastic. Prior art plastic reinforcements usually require a separate and costly molding step or parts which must be attached to the plastic pallet after thermoforming.
What is needed is an all-plastic pallet which may be formed by a twin-sheet thermoforming process with reinforcing plastic portions provided at areas of intense wear.